2021-2023 BMW Z4 Convertible Top Fault Code 805090

Symptoms

Owners of 2021-2023 BMW Z4 Roadster vehicles may experience a convertible top that fails to open or close properly. This malfunction is often accompanied by a specific fault code stored in the vehicle's diagnostic system.

Fault Codes / DTCs

When the convertible top does not open or close, diagnostic trouble code (DTC) 805090 may be stored. This code indicates a functional limitation due to a timeout while the convertible top is attempting to open or close.

Code	Description
805090	"Functional limitation, timeout while opening/closing the convertible top"

Diagnosis / Trigger Conditions

The root cause for the BMW Z4 convertible top fault 805090 is identified as the Hall effect sensor falling out of the convertible top linkage. This sensor is crucial for monitoring the position of the convertible top during its operation. When it becomes dislodged, the system loses its ability to track the top's movement, leading to the functional limitation.

Repair Procedure Summary

BMW Service Information Bulletin SIB 54 03 24 outlines the repair process for this convertible top issue. The procedure involves several key steps:

1. Verify Complaint: Technicians first confirm the customer's reported issue regarding the convertible top's functionality.
2. Diagnostic Scan: An approved BMW battery charger is connected to the vehicle, and fault codes are read from the system to confirm the presence of fault code 805090.
3. Access Sensor: The right rear door panel must be carefully removed to gain access to the convertible top linkage and the Hall effect sensor. This step requires following specific instructions detailed in ISTA/AIR 51 43 000.
4. Sensor Replacement: The faulty Hall effect sensor, labeled as 'D' in the service bulletin's diagrams, is replaced. Technicians are instructed to inspect the condition of the sensor before removal.
5. Verification: After replacing the sensor and reassembling the vehicle, the repair is verified to ensure the convertible top operates correctly.

Required Tools or Parts

The primary part required for this repair is the Hall effect sensor. The specific part number is:

• Part Number: 54 34 5 B65 108
• Description: Magnet, Hall effect sensor
• Quantity: 1

Additional small parts, fluids, lubricants, and one-time use fasteners may also be required, which should be sourced from the Electronic Parts Catalog (ETK) or other approved BMW Group resources.

Important Warnings

BMW notes that "THIS REPAIR IS MOBILE FRIENDLY," indicating that the necessary work can be performed with relative ease in a workshop setting.

Owner Action

If your 2021-2023 BMW Z4 is experiencing a convertible top malfunction or displaying fault code 805090, it is recommended to schedule an appointment with an authorized BMW service center. This repair is covered under the terms of the BMW New Vehicle Limited Warranty for Passenger Cars and Light Trucks, or the BMW Certified Pre-Owned Program, as applicable.

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Source: NHTSA ID: 11013048, BMW SIB 54 03 24